1. Field of the Invention
The present invention relates to a compact solenoid, a compact solenoid valve and, a compact latching solenoid valve.
2. Description of the Related Art
In such instruments as an apparatus for chemical examination, environmental analysis, or biotechnological research, it is an important issue to improve accuracy and to minimize a sample or reagent. This issue involves, in each system for mixture, reaction, and detection of fluid, a reduction of the length of fluid channel, a miniaturization of individual components, and a decrease of the entire internal volume of the system. Accordingly, it is also required to miniaturize a solenoid valve, which is broadly used in the fluid control section of the apparatus. Especially when more than one solenoid valves are arranged side by side, the miniaturization of each solenoid valve will directly conduce to a reduction of the length of fluid channel, and therefore, the miniaturization of the solenoid valve can be the most important issue.
Generally, a solenoid valve is comprised of a solenoid, a movable core reciprocably arranged inside the solenoid, a valve element arranged at the leading end of the movable core, and so on. The solenoid includes a coil and a frame located outside of the coil. The frame is fabricated of a magnetic material thereby constitutes a magnetic circuit.
The frame is categorized into two types; an open frame and a closed frame. The closed frame 5A illustrated in FIGS. 12A, 12B and 12C has a hollowed cylindrical shape, and covers all over the outer circumference 14A of the coil 1A. The open frame 5B illustrated in FIGS. 14A, 14B, 14C and 14D has a U-shaped vertical section. Assuming that the outer circumference 14B of the coil 1B has four sides, the frame 5B covers two of them. One example of the open frame is disclosed in JP 2001-178104 A.
If four compact solenoid valves employing a compact solenoid with a closed frame 5A are arranged side by side, as shown in FIG. 13, the footprint of the four compact solenoid valves is 81 mm2, provided that the outer diameter of the coil 1A is 4 mm and the outer diameter of the frame 5A is 4.5 mm.
If four compact solenoid valves employing a compact solenoid with an open frame 5B are arranged side by side, as shown in FIG. 15, the footprint of the four compact solenoid valves is 75.2 mm2, provided that the outer diameter of the coil 1B is 4 mm and the width of the frame 5B is 4.7 mm.
As has been described above, conventional compact solenoids have large footprints.